With very limited success, wheelchairs have been adapted to access areas requiring travel over soft terrain, such as sand, loose soil and gravel. Attempts at designing beach wheelchairs, in particular those described in U.S. Pat. No. 4,641,850, to Rice et al., provided removable wide metal bands surrounding the propulsion wheels of the wheelchair so as to keep the wheels from sinking in the sand. However, such beach wheelchairs and their additional parts would invariably sink into the sand and get fouled and the metal in such chairs would corrode in the salt air. Further, the front wheels or casters would sink into the sand anyway, dragging the user and her dignity down with them. Still further, once the user accessed the beach, she still had to negotiate her way into and out of the water by exiting and then re-entering the wheelchair.
Compounding the indignity caused by immobile, corrosable and easily fouled beach wheelchairs, existing beach wheelchairs fold like an accordion and their frames often start folding on their own during the user's struggle to travel on the sand. The wheelchairs thus fail to support the user properly and can thereby cause muscle and back strain. As if this were not enough indignity, the seating materials of existing beach wheelchairs do not breathe and can cause chafing and discomfort.
A recent low pressure tire design, described in U.S. Pat. No. 6,279,631, to Tuggle, provides a fairly inelastic low pressure tire material for a beach wheelchair that can flatten under load to ease movement over soft surfaces. However, the low pressure tire concept does not solve the problem of fouling or corrosion and does not address the problem caused when any tires, front or rear, sink in the sand. Further, the low-pressure tire concept does not address the need to provide an easy to fold wheelchair that does not fail to support the user when in use. Still further, no seat materials are taught or suggested which prevent chafing and irritation to the user.
There remains great and long felt demand for a wheelchair that allows easy travel over soft ground and sand and which will not corrode in the salt air. As well, wheelchair users continue to desire comfortable seat materials that breathe. Still further, an easy to fold, lightweight wheelchair frame would enhance ease of use in comparison to existing accordion-style folding beach wheelchairs. Finally, wheelchair users still lack for a beach wheelchair that allows easy exit and re-entry to permit them to get on the beach or enter the water. Accordingly, the present inventors have sought to provide a wheelchair that solves the aforementioned problems while respecting the user's dignity.